Branched low profile additives and methods of production

ABSTRACT

The invention pertains to low profile additives (“LPA”) comprising branched polymers having a weight average molecular weight (Mw) of at least about 20,000 grams/mole and a number average molecular weight (Mn) of at least about 3,000 grams/mole and methods for making the LPAs. The invention further concerns compositions comprising LPAs synthesized from one or more difunctional monomers and one or more branching agents. Also, disclosed are thermosettable resinous compositions and molded articles comprising the LPAs.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to low profile additives (“LPAs”) comprising branched polymers and methods for making the LPAs. The invention further concerns thermosettable resinous compositions, e.g., sheet molding compound (“SMC”) and bulk molding compounds (“BMC”), comprising the LPAs.

2. The Related Art

Polyester resins and vinyl ester resins may be used for thermosetting resin materials. Thermosetting unsaturated polyester resins are generally prepared by reacting dicarboxylic acids and anhydrides with glycols. Thermosetting vinyl ester resins are typically the reaction product of about equal amounts of a polyepoxide and an unsaturated monocarboxylic acid. When applied to thermosetting compositions, polyester and vinyl ester resins may be used in combination with fibrous reinforcement and inert fillers to manufacture composite structures, such as SMC and BMC. Such composite structures may be made by pre-mixing the resin, filler, fibrous reinforcement, and other additives to form the molding compound. For SMC, in particular, the resin, filler, initiator, and other additives can be mixed to form a paste, which is then sandwiched between two rolling polyethylene sheets, one of which is covered with chopped fiberglass reinforcements. Resinous paste wets the fiberglass and the whole mixture gets compacted while passing through a series of calendering rolls to form the SMC. BMC, on the other hand, is prepared by premixing resin, filler, and other additives to form a molding paste. Fibrous reinforcements are then added to the paste and mixed to form the BMC. The molding compound then can be formed into the desired shape and cured in a heated, matched metal die.

Chemical thickening of the relatively low viscosity liquid resin, e.g., with a Group II metal oxide or hydroxide and water, to form a high viscosity gel after the resin has been mixed with all other ingredients in the molding compound can be applied in the manufacture of SMC or BMC. This thickening or B-staging has several advantages. Unthickened molding compounds are sticky masses, which are difficult to handle. After B-staging, they are firm to very high viscosity solid-like gels whose surfaces are relatively dry, and may appear like leathery sheets, like in the case of SMC. In this form, the compound can be handled easily. During the molding operation, the molding compound flows within the die set to fill the die cavity. The increased viscosity of B-staged molding compounds inhibits segregation of the various components of the molding compound during flow and promotes compositional uniformity of the composite over the entire volume of the structure.

Thermosetting resins shrink in volume during ‘cure’. This shrinkage can cause warpage, internal stress build-up, dimensional changes, and poor surface cosmetics when reinforced composite objects are made from these thermosetting resins. Thermoplastic additives, typically referred to as LPAs, are known to reduce ‘cure shrinkage’ and associated problems. There are several types of polymers that may be used as LPAs, including saturated polyesters, polystyrene, poly(methylmethacrylate), poly(vinylacetate), and the like. Saturated polyester LPAs are generally linear polymers made primarily from aliphatic dibasic acids or anhydrides, like adipic acid or succinic anhydride, and diols, such as ethylene glycol, propylene glycol, or diethylene glycol. Linear LPAs made with high levels of aromatic diacids, like various phthalic diacids and anhydrides, and mixtures of symmetrical and asymmetrical diols, as well as those prepared with the addition of trimellitic anhydride, are also disclosed in the art.

SUMMARY OF THE INVENTION

The LPAs of this invention are prepared by reacting one or more monomers, such as typical difunctional monomers like diacids and diols with one or more branching agents. For purposes of this specification and the appended claims, branching agents shall mean multifunctional molecules, which contain or generate functional groups capable of further reacting with themselves or difunctional monomers to cause branching. The branching agent may be generative type or non-generative type and can also be a complex molecule having both generative and non-generative functionalities, i.e. the generative/non-generative type. The branching agent may be combinations of these types.

Diepoxides are examples of a generative type of branching agent. Upon their reaction with diacid monomers generative type branching agents are incorporated into the polymer backbone with concomitant formation of hydroxyl groups. The hydroxyl groups subsequently act as sites for branching through their reaction with any available carboxylic acid groups. Generative type branching agents also include dianhydrides, such as ethylene glycol bis(trimellitic anhydride) or pyromellitic dianhydride. Upon their reaction with hydroxyl groups the dianhydrides are incorporated into the polymer structure with concomitant formation of carboxyl groups. Carboxyl groups thus formed act as sites for branching through their reaction with any available hydroxyl groups.

Non-generative branching agents are typically multifunctional molecules having functionality greater than two and include, but are not limited to, polyols (e.g. glycerol, trihydroxymethylol propane, pentaerythritol, etc.), polyacids (e.g. trimelitic acid), polyhydroxyacids (e.g. 2,2-bis(hydroxymethyl)propionic acid, malic acid, citric acid, tartaric acid, etc.) and the like. The generative/non-generative branching agents are structurally more complex molecules that combine features of generative and non-generative branching agents (e.g. glycidol, epoxydized fatty acids, trimellitic anhydride, and the like). The branched structure of polyester allows the formation of high molecular weight LPA at a lower solution viscosity. In addition, these branched polyester LPAs are more effective at reducing shrinkage caused by cure, and improving surface smoothness of the molded objects.

The method for making the branched LPAs comprises reacting one or more branching agents with one or more monomers, typical polyester monomers, to produce LPAs with high polydispersity and relatively high weight average molecular weight. The method of making the branched LPAs produce high weight average molecular weight LPAs at lower solution viscosity, as compared to their linear analogues. Among many advantages of the method is the ability to make branched LPAs in which the manufacturing cycle time is significantly reduced. In an example of the method, one or more generative branching agents are mixed with an esterification catalyst and monomers, such as both diacid and diol monomers, at the beginning of the reaction. The mixture is then heated, typically at temperatures of about 120° C. to about 230° C., and allowed to react, resulting in immediate and fast branching and molecular weight buildup. In another example, a branching agent selected from the group consisting of one or more non-generative type branching agent, one or more complex generative/non-generative type branching agent comprising both generative and non-generative functionalities, and combinations thereof, are mixed simultaneously with esterification catalysts, and monomers, such as both diacid and diol monomers, and allowed to react under the typical polyesterification conditions.

The branched LPAs may be used in molding compounds and molded articles. In embodiments of the invention the LPAs described herein, including those made by the methods described herein, can be combined with components of molding compounds such as resin, filler, fibrous reinforcement, and other additives and the like to form a compound, which can then be molded into parts. Preferred resins include unsaturated polyester resins, vinyl ester resins, and mixtures thereof. For example, SMC and BMC comprising the branched LPAs provide improved surface quality of molded articles made from such SMC and BMC.

DETAILED DESCRIPTION OF THE INVENTION

The branched LPAs made using branching agent have relatively high weight average molecular weight and relatively high polydispersity. The weight average molecular weight (Mw) of the LPA is generally at least about 20,000 g/mol, such as from about 20,000 g/mol to about 1,000,000 g/mol, and typically from about 50,000 g/mol to about 300,000 g/mol. The number average molecular weight (Mn) is generally at least about 3,000 g/mol, typically from about 3,000 g/mol to about 10,000 g/mol. The polydispersity of the branched LPAs is generally at least about 4, such as about 4 to about 100, typically from about 5 to about 50, and most preferably about 7 to about 40.

In an embodiment of the invention, the branched LPAs are branched polyester LPAs which can be made using saturated aliphatic and aromatic diacids and anhydrides thereof. Suitable aliphatic diacids include, for example, succinic acid, succinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedionic acid, dodecanedionic acid, cyclohexane dicarboxylic acid, and the like, and mixtures thereof. Dimer acids, such as UNIDYME® line of products from the Arizona Chemical Company, Jacksonville, Fla., U.S.A. can also be used. Suitable aromatic diacids include, for example, phthalic acid, phthallic anhydride, isophthalic acid, terephthalic acid, bisphenyl-4,4′-docarboxylic acid, diphenic acid, 2,6-naphthalene dicarboxylic acid, and the like, and mixtures thereof. Mixtures of aliphatic and aromatic diacids also can be used.

Glycols may be used in making the branched polyester LPAs and these include, for example, HO—(CH₂)_(n)—OH, where n is 2 to 10; HO—(CH₂—CH₂—O—CH₂—CH₂)_(n)—OH, where n is 1 to 10; HO—(CH₂—CH(CH₃)—O—CH₂—CH(CH₃))_(n)—OH, where n is 1 to 10. Cyclic and bicyclic glycols, such as, cyclohexane diol and isosorbide, can also be used. Specific glycols used in formulating the branched polyester LPAs include, for example, ethylene glycol, 1,2- and 1,3-propylene glycols, butanediol, hexane diol, 2-methyl-1,3-propanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,3-propanediol and the like, and combinations thereof. 1,3-propanediol (Bio-PDO) available from DuPont Tate & Lyle Bioproducts Co. LLC, such as that available under the trade name SUSTERRA™, may be used.

Branched polyester LPAs are made by reacting typical diacid and diol monomers with one or more branching agents, such as the generative type, non-generative type, and/or generative/non-generative type branching agents. The branching agents will have degree of functionality greater than or equal to two, that is comprises two or more functional groups. Branching agents can have one or more different types of functional groups incorporated into their structure. Such functional groups include, but are not limited to anhydride, hydroxy, carboxy, epoxy, and ester functional groups. Branching agents cause a branched polymer structure during the reaction. Branching agents useful for the invention include polyacids, polyols, epoxy resins, polyhydroxyacids, the mixtures thereof, and the like. Examples of such branching agents are: glycerol, pentaerythritol, trimethylolpropane, polyetherpolyols, polyester polyols, vegetable oil-based polyols and mixtures thereof; polyepoxides, typically aliphatic and/or aromatic polyepoxides, such as, polyglycidyl ethers of polyphenols, like bisphenol A, bisphenol-F, 1,1-bis(4-hydroxy phenyl)ethane, 1,1-bis(4-hydroxy phenyl)isobutane, and 1,5-dihydroxy naphthalene, modified epoxy resins with acrylate or urethane moieties, glycidylamine epoxy resins, novolac epoxy resins; commercial bisphenol epoxy resins, such as, EPON® 826 and EPON® 828 from Hexion Specialty Chemicals, Inc., Houston, Tex., U.S.A. (“Hexion”) and epoxy resins D.E.R.™ 383, and D.E.R.™ 364, as well as commercial epoxy novolac resins, like D.E.N.™ 431, 438 and 439 from the Dow Chemical Company, Midland, Mich., U.S.A. (“Dow”); epoxidized vegetable oils, such as commercially available epoxidized soybean oil (PLAS-CHEK® 775) from Ferro Corp., Cleveland, Ohio, U.S.A. or VIKOFLEX® 7190 epoxidized linseed oil from Arkema Inc, Philadelphia, Pa., U.S.A., hydroxy-containing vegetable oils, such as castor oil, polyfunctional monomers containing more than one type of functional groups, such as glycidol, 2,2-bis-(hydroxymethyl)propionic acid, citric acid, malic acid, tartaric acid, and the like.

In embodiments, the LPA comprises about 0.1 mole % to about 10 mole % of branching agent, based on the amount of total monomers, as such amounts are generally used in making the LPA. Preferably, the branching agent is used in amounts ranging from about 1 mole % to about 5 mole % based on the total amount of monomers, typically about 1.5 mole % to about 4 mole % based on the total amount of monomers.

In making the LPA, generally, the temperature of esterification is maintained in the range of about 150° to about 230° C. and an esterification catalyst is used. Such catalysts are conventional and include, for example, titanium tetrachloride, zinc acetate, zinc oxide, stannous oxalate, dibutyl tin oxide, phosphoric acid and the like and combinations thereof. Conventional color stabilizers, e.g., trilauryl phosphite or the like, also can be included in the reaction mixture.

The LPAs may be incorporated into SMC and BMC. For example, unsaturated polyester resins are suitable for making molding compounds for use with the branched LPAs. U.S. Pat. No. 5,552,478 describes thermosetting unsaturated polyesters and processes for making them. This patent also describes solvents (ethylenically unsaturated compounds), other than styrene, that can be used, such as, for example, vinyl toluene, methacrylic esters, and the like, and mixtures thereof.

Additionally, the LPAs can be incorporated into the vinyl ester or unsaturated polyester composite compositions. Accordingly, suitable curing agents (e.g., peroxides, such as, for example tert-butyl peroxyperbenzoate), accelerating agents, and the like are incorporated. Reinforcement and inert additives and fillers such as glass, metal filings, and inorganic fillers such as sand or clay also are appropriate. Pigments, release agents, plasticizers, and the like also are used as is necessary, desirable, or convenient in conventional fashion. Further, one or more enhancers, such as those described in U.S. Pat. Nos. 5,504,151 and 6,617,394, may be incorporated to further improve the surface quality. The enhancer may be applied as an additive in formulating the composite composition or may be mixed with the LPA and this mixture is incorporated. Enhancers suitable for the invention include all those described in U.S. Pat. Nos. 5,504,151 and 6,617,394, for example tall oil fatty acid capped adipic acid diethylene glycol oligomers, octyl epoxy tallate (such as DRAPEX® 4.4 available from Chemtura Corporation, Middlebury, Conn., U.S.A.), epoxidized linseed oil (such as FLEXOL™ LOE available from the Dow Chemical Company, Midland, Mich., U.S.A.), tall oil fatty acid capped multi functional epoxy, fatty acid capped multi functional polyols like polyethylene glycol dilaurates and polyethylene glycol dioleates (such as ETHOX DL-9, ETHOX DO-9 and ETHOX DO-14 available from Ethox Chemicals, Greenville, S.C., U.S.A.) and combinations thereof, and the like.

Composite compositions include SMC and BMC comprising some or all of (a) one or more resin, such as unsaturated polyester resin, vinyl ester resin or mixtures thereof, (b) one or more branched LPAs, either separately or in a mixture with one or more conventional or other LPAs, such as polyvinyl acetate, polystyrene, polymethyl methacrylate and the like, (c) one or more unsaturated monomer copolymerizable with the unsaturated polyester or vinyl ester, (d) fillers, (e) reinforcing fiber, (f) other additives and catalysts, (g) enhancers and (h) inhibitors. The total amount of LPA solids in the formulation ranges from between about 5 to about 35 parts per 100 weight parts of thermoset mixture, i.e. resin, the LPA(s), and the unsaturated monomer. The total amount of LPA in the composite composition is comprised of from about 1% to 100% of the branched LPA by weight of the total amount of LPA, and in embodiments where the composite composition comprises other LPA(s) in addition to the branched LPA, the amount of the other LPA(s) is up to about 99% by weight of the total amount of LPA, typically about 1% to about 99%. The SMC and or BMC, or other material comprising the LPA, may be used to make molded articles, such as molded articles comprising the LPA disclosed herein.

The LPAs described herein having the higher molecular weights provide for a more efficient additive and generally exhibit better shrinkage control and higher quality cosmetic surface when formulated with resins. The LPAs also exhibit better physical properties.

The following examples show how the present invention has been practiced, but should not be construed as limiting. In this application, all percentages and proportions are by weight and all units are in the U.S. system, unless otherwise expressly indicated. Also, all citations, including all patents and published patent applications referenced in this specification are expressly incorporated in their entirety herein by reference.

EXAMPLES 1 THROUGH 4

The following raw materials, as set forth in Table 1, were charged to a three-liter resin kettle equipped with a thermocouple, mechanical stirrer, a fractionating column, distillation head, a condenser, and a nitrogen sparge to make branched LPAs.

TABLE 1 Example Component Grams Moles Mole-% 1 Ethylene glycol 421.05 6.78 25.40 Propylene glycol 521.40 6.85 25.66 Adipic acid 1837.80 12.58 47.09 EPON 828 Resin* 187.25 0.49 1.85 2 Diethylene glycol 149.00 1.40 7.40 Ethylene glycol 417.40 6.72 35.50 PPG 410 366.60 1.21 6.39 EPON 828 Resin* 60.00 0.16 0.85 Adipic acid 1,379.20 9.44 49.86 3 Stage I Ethylene glycol 209.60 Propylene glycol 490.77 NPG 180.10 EPON 828 Resin* 60.00 Adipic acid 292.00 Stage II Isophthalic Acid 1182 g 4 Ethylene glycol 253.57 Propylene glycol 310.11 Adipic acid 1,201.92 EPON 828 Resin* 31.28 *EPON ® 828 difunctional bisphenol A/epichlorydrin derived liquid epoxy resin, epoxide eq. 185-192, viscosity @ 25° C. 110-150; Hexion Specialty Chemicals, Inc., Houston, TX

The mixture in each example was heated slowly to 120° C. at which time about 2.0 g to 2.5 g of triphenyl phosphine and about 2.0 g to about 2.5 g of FASCAT® 4100 butylstannoic acid (CAS 2273-43-0, Arkema Inc, Philadelphia, Pa.) catalysts were added. The now homogeneous mixture was heated slowly to 215° C. removing water. The reaction mixture was sparged with nitrogen. The rate of sparge was maintained such that the distillation head temperature is kept at 100° C. throughout the removal of water. The acid number and viscosity of the resin was monitored during the reaction. When the acid value reached 11-13 and the viscosity of the polyester (C&P at 150° C.) was at 6.0 to 7.0 Poise, the reaction product was cooled and cut to 60% nonvolatiles solids in styrene and inhibited with 200 ppm tert-butylcatechol. Examples 1 and 4 were analyzed for molecular weight and polydispersity. The LPA of example 1 had a weight average molecular weight (Mw) of 82,000 g/mol, a number average molecular weight (Mn) of 4,200 g/mol and a polydispersity of 19.5. The LPA of example 4 had a weight average molecular weight (Mw) of 27,670 g/mol, a number average molecular weight (Mn) of 5,560 g/mol and a polydispersity of 5.0.

EXAMPLE 5

SMC was formulated by conventional methods using the branched LPA prepared in accordance with Example 1. The following table, Table 2, shows SMC formulations using the branched LPA and the properties of molded panels comprising the SMC. The SMC sheet was made according to conventional methods using a 24 inch SMC machine. Panels (12″×12″) were molded at 300° F. (150° C.) and 75 tons pressure for two minutes. Surface quality measurements using Ashland's Advance Laser Surface Analyzer are also shown in Table 2.

TABLE 2 Formulation A B C D UPE Resin AROPOL D 61.1 61.1 61.07 61.07 1691 (Ashland, Inc.) Branched LPA (60% 20.5 29.3 10.06 20.5 NV) PVAc LPA (40.5% NV) 0.00 0.00 17.28 0.0 Styrene 18.4 9.6 11.39 18.4 Total 100.0 100.0 100.00 100.00 Filler (CaCO₃) 200.0 200.0 200.00 200.00 Enhancesrs 0.00 0.00 4.00 4.00 Wetting agent (BYK 0.6 0.6 0.6 0.6 9010, Byk Chemie) Mod E (5% p- 0.2 0.2 0.2 0.2 benzoquinone solution) BHT (butylated hydroxyl 0.02 0.02 0.02 0.02 toluene) TBPB Initiator (tert-butyl 1.5 1.5 1.5 1.5 peroxyperbenzoate) Zn Stearate 4.5 4.5 4.5 4.5 Total weight A side 306.8 306.8 310.8 310.8 B-side (Mod M, 2.70 2.70 2.74 2.74 Ashland Inc.) 1″ Glass % (1″ hard 27-28 27-28 27-28 27-28 chop glass, Owens Corning) Surface quality ALSA Ashland Index 54.2 44.5 42.9 45.2 ALSA DOI 99.3 99.0 97.0 98.3 ALSA OP 8.8 9.0 8.9 8.9 Expansion 0.00065 0.00083 0.00096 0.0009 *Enhancing additives are Ashland Inc. products such as those described in U.S. Pat. Nos. 5,504,151 and 6,617,394.

EXAMPLE 6

Branched LPA containing component(s) that requires transesterification digestion) was made with the following components as set forth in Table 3.

TABLE 3 EX. 6 Component g mole mole % Ehylene Glycol 341.37 5.50 23.78 Propylene Glycol 418.50 5.50 23.78 Adipic Acid 1607.54 11.00 47.55 Soybean oil 572.00 0.65 2.81 Epon ® 828 Resin 170.13 0.45 1.94 Zinc Acetate 1.33 0.006 0.03 HQ 0.30 0.003 0.01 TPP 2.93 0.011 0.05 FASCAT 4100 3.03 0.015 0.06

The procedure for Example 6 was as follows. Ethylene glycol, propylene glycol, soybean oil, and zinc acetate were added to a 3 L reactor equipped with a Vigreux column and a water condenser. Reaction was heated to 190-200° C. and temperature maintained for two hours to allow transesterification of soybean oil. A portion of adipic acid was then added to the reactor and the temperature increased to 200° C. After about 100 g of water was removed, reaction temperature was lowered below 140° C. and EPON® 828 resin, triphenyl phosphine (TPP), and the rest of the adipic acid, were added to the reactor. Reaction was then permitted to proceed at 200® C. until the acid value of 10-13 and C/P viscosity of 6-7 Poise at 150° C. were reached. The polyester LPA was diluted with 1,136 grams of ST, inhibited with 0.768 grams of tert-butylcatechol (TBC) (85% solution in methanol) and 0.786 grams of hydroquinone (HQ) to give LPA resin with 70.5% nonvolatiles.

The polydispersity index of LPAs were evaluated using conventional gel permeation chromatography (GPC). Example 6 had a number average molecular weight of 5,680 g/mol, weight average molecular weight of 319,461 g/mol, and polydispersity index of 56.2.

EXAMPLE 7

The following procedure describes the use of non-generative branching agent for the synthesis of a branched LPA of this invention. The following raw materials, as set forth in Table 4, were charged to a three-liter resin kettle equipped with a thermocouple, mechanical stirrer, a fractionating column, distillation head, a condenser, and a nitrogen sparge to make branched the LPA.

TABLE 4 EX. 7 Component g mole mole % Ehylene Glycol 420.82 6.78 24.42 Propylene Glycol 521.22 6.85 24.67 Adipic Acid 1968.44 13.47 48.52 Glycerol 60.17 0.65 2.34 FASCAT 4100 2.51 0.012 0.04

All components listed in Table 4 were charged into the reactor and heated slowly to 215° C. with concomitant removal of water. After the overhead temperature dropped below 75-80° C., the fractionating column was removed and reaction mixture sparged with nitrogen. When the acid value reached 10-13 and the C/P viscosity at 175° C. reached 6-7 Poise, the reaction was cooled down below 80° C. and dissolved in styrene inhibited with 200 ppm of tert-butylcatechol to 60% nonvolatiles. The LPA of example 7 had a weight average molecular weight (Mw) of 41,809 g/mol, a number average molecular weight (Mn) of 5,282 g/mol and a polydispersity of 7.92.

EXAMPLE 8

SMC was formulated by conventional methods using the branched LPA prepared in accordance with Example 7. The following table, Table 5, shows SMC formulations using the branched LPA and the properties of molded panels comprising the SMC. The SMC sheet was made according to conventional methods using a 24 inch SMC machine. Panels (12″×12″) were molded at 300° F. (150° C.) and 75 tons pressure for two minutes. Surface quality measurements using Ashland's Advance Laser Surface Analyzer are also shown in Table 5.

TABLE 5 Formulation A UPE Resin AROPOL ™ D 1691 61.1 (Ashland, Inc.) Branched LPA from EX. 7 (60% NV) 29.3 Styrene 9.60 Total 100.0 Filler (CaCO₃) 200.0 Wetting agent (BYK 9010, Byk 0.6 Chemie) Mod E (5% p-benzoquinone solution) 0.2 BHT (butylated hydroxyl toluene) 0.02 TBPB Initiator (tert-butyl 1.5 peroxyperbenzoate) Zn Stearate 4.5 Total weight A side 306.8 B-side (Mod M, Ashland) 2.70 1″ Glass % (1″ hard chop glass, 27-28 Owens Corning) Surface quality ALSA Ashland Index 58.7 ALSA DOI 97.3 ALSA OP 8.4 Expansion 0.00060

EXAMPLES 9-14

Branched polyester LPAs containing reactants difficult to solubilize, such as tere-phthalic acid (t-PA), were synthesized in a two stage process. About 2,500 g of branched polyester LPA was prepared in each example. The compositions formulated in these examples are set forth in Tables 6 and 7.

TABLE 6 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Reactant Wt (g) Wt (g) Wt (g) Wt (g) Wt (g) Stage 1 Ethylene glycol 380.2 300.0 315.0 552.5 467.5 Diethylene glycol 650.1 526.8 526.8 856.05 724.35 t-PA 974.6 781.4 781.4 1,269.78 1,074.43 FASCAT ® 4201 2.5 2.0 2.0 3.25 2.75 Stage 2 Adipic Acid 857.2 740.4 740.4 1,203.15 1,018.05 Bis-A Epoxy 125.0 60.0 120.0 162.5 137.5 TPP 2.5 2.0 2.1 3.5 3.0

TABLE 7 Ex. 14 Reactant Wt. (g) Stage 1 Susterra ™ Propanediol (DuPont 416.65 Tate&Lyle Bio Products Co. LLC) Diethylene Glycol 526.80 t-PA 781.40 FASCAT ® 4201 2.20 Stage 2 Adipic Acid 778.22 Bis-A Epoxy 100.00 TPP 2.20

Stage I

t-PA and glycols raw materials were charged into a the three-liter resin kettle equipped with a thermocouple, mechanical stirrer, a fractionating column, distillation head, a condenser and a nitrogen sparge. The reaction mixture, a white milky dispersion of solid t-PA in glycol, was heated with stirring to 195° C. to 200° C. to facilitate dissolving the t-PA into the glycol. Water was removed through the distillation column and when the glycols and t-PA had reacted to form a low molecular weight, clear, liquid oligomer, Stage I was complete.

Stage II

The heat was turned off and the adipic acid and Epoxy were charged, reducing the reactor temperature to approximately 140° C. The TPP (triphenylphosphine) catalyst was charged and the reaction mixture was held at 135° C. to 145° C. to react the epoxy and acids. The homogeneous mixture was then heated slowly to 215° C., while removing water. The reaction mixture was sparged with nitrogen. The rate of sparge was maintained such that the distillation head temperature was kept at 100° C. throughout the removal of water. The acid number and viscosity of the resin was monitored during the reaction. When the acid value reached 10-13 and the cone and plate viscosity of the polyester was between 6 and 8 Poise at 175° C., heating and sparging were stopped. The reaction product was cooled down and cut to 60% nonvolatiles in styrene and inhibited with 100 ppm PBQ and 100 ppm tert-butylcatechol.

COMPARATIVE EXAMPLE 15 AND EXAMPLE 16

SMC and molded panels were made with conventional LPA, ENVIREZ® 2431 from Ashland, Inc., Dublin, Ohio, U.S.A., (Comparative Example 15) and branched LPA (described in Example 10) prepared in accordance with the invention (Example 16). The LPAs were each combined with AROTRAN® 185 resin and conventional fillers and additives, including polyvinyl acetate to make SMC sheet according to the standard methods using 24 inch SMC machine. Panels (12″×12″) were molded at 300° F. (150° C.) and 75 tons pressure for two minutes. The table shows the surface quality for molded panels from SMC formulations using ENVIREZ® 2431 LPA and branched polyester LPAs and measured by Ashland's Advanced Laser Surface Analyzer (ALSA).

TABLE 8 EX. 15 EX. 16 Molding Viscosity(MM cP) 48.0 26.8 ALSA Index 53.9 45.1 DOI 84.7 97.3 Orange Peel 7.7 8.8 

1. A low profile additive comprising a branched polyester resin wherein the low profile additive has a weight average molecular weight (Mw) of at least about 20,000 grams/mol and a number average molecular weight (Mn) of at least about 3,000 grams/mol.
 2. The low profile additive of claim 1 having a polydispersity of at least about
 4. 3. The low profile additive of claim 1 wherein the branched polyester resin is in admixture with at least one copolymerizable monomer.
 4. A composition comprising a low profile additive synthesized from one or more difunctional monomers and one or more branching agents.
 5. The composition of claim 4 wherein the difunctional monomer is a saturated aliphatic diacid or an anhydride thereof.
 6. The composition of claim 5 wherein the saturated aliphatic diacid is selected from the group consisting of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedionic acid, dodecanedionic acid, cyclohexane dicarboxylic acid, a dimer acid, and combinations thereof.
 7. The composition of claim 4 wherein the difunctional monomer is a saturated aromatic diacid or an anhydride thereof.
 8. The composition of claim 7 wherein the saturated aromatic diacid is selected from the group consisting of phthalic acid, isophthalic acid, terephthalic acid, bisphenyl-4,4′-docarboxylic acid, diphenic acid, 2,6-naphthalene dicarboxylic acid, and combinations thereof.
 9. The composition of claim 4 wherein the difunctional monomer is a glycol.
 10. The composition of claim 9 wherein the glycol is selected from the group consisting of HO—(CH₂)_(n)—OH, where n is 2 to 10; HO—(CH₂—CH₂—O—CH₂—CH₂)_(n)—OH, where n is 1 to 10; HO—(CH₂—CH(CH₃)—O—CH₂—CH(CH₃))_(n)—OH, where n is 1 to 10, cyclic glycol, bicyclic glycol and combinations thereof
 11. The composition of claim 9 wherein the glycol is selected from the group consisting of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, butanediol, hexane diol, 2-methyl 1,3-propanediol, dipropylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, cyclohexane diol, isosorbide and combinations thereof.
 12. The composition of claim 4 wherein branching agent comprises two or more functional groups.
 13. The composition of claim 12 wherein the functional groups are selected from the group consisting of anhydride, hydroxy, carboxy, epoxy, esters and combinations thereof.
 14. The composition of claim 4 wherein the branching agent is selected from the group consisting of polyacids, polyols, epoxy resins, polyhydroxyacids and combinations thereof.
 15. The composition of claim 4 wherein the branching agent is selected from the group consisting of glycerol, pentaerythritol, trimethylolpropane, polyetherpolyols, polyester polyols, vegetable oil-based polyols, polyepoxides, epoxidized vegetable oils, hydroxy-containing vegetable oils, polyfunctional monomers containing more than one type of functional group and combinations thereof.
 16. The composition of claim 15 wherein the polyepoxides are selected from the group consisting of polyglycidyl ethers of polyphenols, 1,5-dihydroxy naphthalene, modified epoxy resins with acrylate or urethane moieties, glycidylamine epoxy resins, novolac epoxy resins and combinations thereof.
 17. The composition of claim 16 wherein the polyglycidyl ethers of polyphenols are selected from the group consisting of bisphenol A, bisphenol-F, 1,1-bis(4-hydroxy phenyl)ethane, 1,1-bis(4-hydroxy phenyl)isobutene and combinations thereof.
 18. The composition of claim 15 wherein the polyfunctional monomers containing more than one type of functional group are selected from the group consisting of glycidol, 2,2-bis-(hydroxymethyl)propionic acid, citric acid, malic acid, tartaric acid, and combinations thereof.
 19. The composition of claim 15 wherein the epoxidized vegetable oil is selected from the group consisting of epoxidized soybean oil and epoxidized linseed oil.
 20. The composition of claim 15 wherein the hydroxy-containing vegetable oil is castor oil.
 21. The composition of claim 4 wherein the low profile additive is synthesized with about 0.1 mole % to about 10 mole % of one or more branching agents.
 22. A composite material comprising the low profile additive of claim
 1. 23. The composite material of claim 22 further comprising an unsaturated polyester resin, vinyl ester resin, or mixtures thereof, one or more unsaturated monomers copolymerizable with the unsaturated polyester or vinyl ester resin, and reinforcing fibers.
 24. The composite material of claim 23 further wherein the amount of low profile additive is between about 5 to about 35 parts solid per 100 weight parts of the total amount of resin, the low profile additive and the unsaturated monomer.
 25. The composite material of claim 22 further comprising an other low profile additive.
 26. The composite material of claim 25 wherein the other low profile additive is selected from the group consisting of polyvinyl acetate, polystyrene, polymethyl methacrylate and combinations thereof.
 27. The composite material of claim 22 further comprising one or more enhancers.
 28. The composite material of claim 27 wherein the enhancer is selected from the group consisting of tall oil fatty acid capped adipic acid diethylene glycol oligomers, octyl epoxy tallate, epoxidized linseed oil, tall oil fatty acid capped multi functional epoxy, fatty acid capped multi functional polyols and combinations thereof.
 29. A molded article comprising the composite material of claim
 22. 30. A method of making a branched low profile additive comprising the step of reacting one or more branching agents with one or more monomers resulting in a branched polymeric low profile additive having a weight average molecular weight (Mw) of at least about 20,000 grams/mol and a number average molecular weight (Mn) of at least about 3,000 grams/mol.
 31. The method of claim 30 wherein the branching agent is a generative type and the method comprises the additional steps of mixing the branching agent with an esterification catalyst and the monomer and then heating the mixture.
 32. The method of claim 31 wherein the esterification catalyst is selected from the group consisting of titanium tetrachloride, zinc acetate, zinc oxide, stannous oxalate, dibutyl tin oxide, phosphoric acid and combinations thereof.
 33. The method of claim 31 wherein the mixture is heated to a temperature of about 120° C. and about 230° C.
 34. The method of claim 30 wherein the branching agent is selected from the group consisting of a non-generative type, a generative/non-generative type, and combinations thereof comprising the additional steps of simultaneously mixing the branching agent, an esterification catalyst and the monomer and then allowing the mixture to react under esterification conditions.
 35. The method of claim 34 wherein the esterification catalyst is selected from the group consisting of titanium tetrachloride, zinc acetate, zinc oxide, stannous oxalate, dibutyl tin oxide, phosphoric acid and combinations thereof.
 36. The method of claim 30 wherein the branching agent is selected from the group consisting of a generative type, a non-generative, a generative/non-generative type, and combinations thereof. 